CN114423795A

CN114423795A - Grafted polyvinyl alcohol polymers, formulations containing the same, and creping methods

Info

Publication number: CN114423795A
Application number: CN202080063922.0A
Authority: CN
Inventors: A.穆斯塔法; D.格洛弗
Original assignee: Buckman Laboratories International Inc
Current assignee: Buckman Laboratories International Inc
Priority date: 2019-09-11
Filing date: 2020-09-03
Publication date: 2022-04-29
Also published as: WO2021050339A1; ZA202201801B; US20210070908A1; US11560443B2; JP7464702B2; CA3151832A1; AU2020347108A1; BR112022004064A2; MX2022002819A; AU2020347108B2; EP4028439A1; JP2022547565A

Abstract

The grafted polyvinyl alcohol polymer includes a polyvinyl alcohol backbone and a plurality of side chains grafted to the polyvinyl alcohol backbone. One or more side chains from the plurality of side chains comprise one or more units selected from: an aliphatic carboxylic acid, an aliphatic amide, an aminoalkyl (meth) acrylate, a hydroxylated alkyl (meth) acrylate, or any combination thereof. The grafted polyvinyl alcohol polymer may be included in a formulation that also includes water, and the formulation may be used as an adhesive in a creping process.

Description

Grafted polyvinyl alcohol polymers, formulations containing the same, and creping methods

This application claims the benefit of prior U.S. provisional patent application No.62/898,719 filed 2019, 9, 11, 35u.s.c. § 119(e), which is incorporated herein by reference in its entirety.

The present invention relates to grafted polyvinyl alcohol polymers and formulations, such as creping adhesive formulations or Yankee dryer coating compositions, comprising the polymers. The invention further relates to a method for creping comprising such a formulation and to a method for imparting adhesive (tack) and release (release) characteristics and/or properties to a creped product. For the purposes of the present invention, the Yankee dryer includes a rotary dryer commonly used for creping. For Yankee coatings (coating), Yankee surfaces, and the like, this includes spin dryer coatings and surfaces.

Background

To form a thin paper web (paper web) from a slurry of water and fibers, the wet web is dewatered and then the dewatered web is at least partially dried. In the manufacture of paper towels (toilet tissue, tissue) and similar paper products, creping is often used on such dewatered webs to impart desired properties (e.g. softness and bulk). Typically, creping is accomplished by transporting or conveying the web on the fabric to a heated rotating drum (sometimes referred to as a Yankee dryer). The web is typically transferred to the adhesive dryer surface of the dryer and carried around the main circumferential portion of the dryer before it reaches the point of release contact of the web from the drum. The release contact zone is equipped with a creping blade against which the web is pushed or pressed backwards in the machine direction of the web and obtains the well-known tissue crepe paper (tissue crepe paper) structure, at which point the resulting creped web is taken off the dryer and collected (usually in rolled form).

Prior to transferring the web to the Yankee dryer, an adhesive composition (sometimes referred to in the industry as a "coating package") is typically applied directly to the dryer surface of the dryer to form an adhesive dryer surface. The creping action typically requires some adhesion (adhesion) of the web to the outer surface of the dryer to achieve a consistent and uniform creping action. Creping adhesives (alone or in combination with release agents or other adjuvants) have been applied to web or dryer surfaces for drying and creping purposes in an effort to provide some balance of adhesion and release between the web and the dryer surface.

In obtaining creping performance, various properties of the creping adhesive may be factors. The degree of adherence of the creping adhesive to the dryer surface of the drum can be another factor that affects creping performance and results. Insufficient adhesion may result in poor creping, sheet floating (sheet floating), poor sheet handling, or other problems, however, excessive adhesion may result in creping blade peel (tacking), web blocking behind the creping blade, web breaks due to excessive tension, or other problems.

Various types of creping adhesives have been used to attach the fibrous web to a rotary dryer, such as a Yankee dryer. Unmodified polyvinyl alcohol ("PVOH") is known and has been used as an adhesive in creping processes. While commonly available and cost effective, it tends to coat dryers with hard and non-uniform films that build up as drying and creping proceed, resulting in non-uniform creping or other problems. Another disadvantage of unmodified PVOH is found in the operation of PVOH at the plant (mill) where PVOH is often obtained off-site and must be shipped to the plant (mill). Due to its molecular weight and its ability to gel in aqueous solutions, the total amount of PVOH in water tends to be low, e.g. 8 wt.%. Thus, PVOH in "concentrated" or bulk quantities (bulk atmosphere) is actually a very low concentration of PVOH, which significantly increases the cost of transporting PVOH to paper mills.

Another disadvantage of aqueous solutions of PVOH is the tendency of these aqueous solutions to increase in viscosity over time. Aqueous solutions of PVOH can reach viscosities as high as 2,000-100,000cP · s based on solids content, degree of hydrolysis and molecular weight, making it difficult to handle PVOH at the plant. Furthermore, at some point (e.g., days to months, depending on the molecular weight and degree of hydrolysis of the PVOH), the aqueous solution of PVOH can irreversibly become a gel, making the PVOH essentially useless as an adhesive composition in a creping process.

Existing graft polymerizations using PVOH have been primarily directed to graft polymerization of vinyl monomers such as vinyl acetate, vinyl pyrrolidone, ethylene, and vinyl esters. Some acrylic monomers have been included in the monomer mixture, however, graft polymerization in the past has found problems with graft polymerization of acrylic monomers because, in the presence of PVOH, the polymerization rate is too high, resulting in very large particles and agglomeration.

In view of the foregoing, there is a need for an improved PVOH composition that addresses the shortcomings discussed above. In particular, it would be desirable to provide a formulation that addresses the drawbacks exhibited by unmodified PVOH in terms of cost and operation. Further, it is desirable to have a PVOH that is more storage stable over time, thereby reducing waste associated with PVOH compositions that gel over time and irreversibly form highly viscous gels. The present invention provides such solutions, including methods and formulations that better address these issues. Further, it is desirable to graft polymerize acrylic monomers in the presence of PVOH polymers to form new grafted polyvinyl alcohol polymers.

Disclosure of Invention

It is a feature of the present invention to provide an improved PVOH formulation. The improved PVOH formulation can be used in a cost effective manner in a paper mill.

It is another feature of the present invention to provide a PVOH-based adhesive that can be present in high concentrations in water-based liquids.

It is a further feature of the present invention to provide an improved PVOH formulation that is storage stable over a long period of time.

It is a further feature of the present invention to provide a PVOH-based formulation that can become more dispersible at high pH (e.g., pH 8, where unmodified PVOH can form an irreversible gel).

It is a further feature of the present invention to provide PVOH-based formulations having low viscosity at various concentrations.

Additional features and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objectives and other advantages of the present invention will be realized and attained by means of the elements and combinations particularly pointed out in the description and appended claims.

In accordance with the present invention, one or more of the foregoing features have been accomplished by providing the grafted polyvinyl alcohol polymer of the present invention. The grafted polyvinyl alcohol polymer has or includes a polyvinyl alcohol backbone and a plurality of side chains grafted to the polyvinyl alcohol backbone. One or more side chains from the plurality of side chains have one or more units selected from: aliphatic carboxylic acids, aliphatic amides, hydroxylated alkyl (meth) acrylates, and/or alkylamino (meth) acrylates, and/or any combination thereof.

The invention further relates to formulations comprising an aqueous phase and the grafted polyvinyl alcohol polymer of the invention. For example, the formulation may consist of 100 parts by weight of the aqueous phase and 10 to 40 parts by weight of the grafted polyvinyl alcohol polymer. The grafted polyvinyl alcohol polymer is dispersed in the aqueous phase.

The invention further relates to a process for the production of the aqueous solution of the grafted polyvinyl alcohol polymer according to the invention. The method may comprise the steps of: adding a base to the dispersion to raise the pH of the dispersion to 4 to 8 or from above 5 to 8 and forming an aqueous solution of the grafted polyvinyl alcohol polymer. In this method, the dispersion includes an aqueous phase and a grafted polyvinyl alcohol polymer dispersed in the aqueous phase. Prior to said adding step, the dispersion may have a pH of 2 to 5 or 2 to 3.

The invention further relates to a process for creping a fibre web. The process may include the steps of: providing a rotating cylindrical dryer (which includes a dryer surface), and applying to the dryer surface a formulation comprising the grafted polyvinyl alcohol polymer of the invention. In the process, the fiber web may be conveyed towards the dryer surface. Further, the fiber web may be dried on a dryer surface to form a dried fiber web, and the dried fiber web may then be creped from the dryer surface (crepe).

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are intended to provide further explanation of the present invention, as claimed.

Detailed Description

The present invention relates to grafted polyvinyl alcohol polymers and formulations comprising the grafted polyvinyl alcohol polymers of the present invention. The formulation may be a creping adhesive formulation or a Yankee dryer coating composition. The adhesive formulation is capable of providing the fibrous web with tack (tack) and release (release) characteristics when the fibrous web is on the Yankee dryer or dryer surface. By "polymer" or "the polymer" herein is meant the grafted polyvinyl alcohol polymer of the present invention, unless otherwise specified.

As used herein, "monomer" (e.g., aliphatic carboxylic acid, aliphatic amide, aminoalkyl (meth) acrylate, hydroxylated alkyl (meth) acrylate, or any combination thereof) refers to a molecule that can react to form a polymer by chemical bonding with a monomer, such as itself or other monomer or monomeric unit or backbone.

As used herein, "monomeric units" or "units" (e.g., units of aliphatic carboxylic acids, etc.) refer to chemically bonded units in a polymer that are derived from monomers.

It should be understood that while monomers or monomer units are described or referenced herein, the graft polymer itself has the radical form of the respective monomer and is thus referred to as a monomeric unit or monomer unit (e.g., a unit of an aliphatic carboxylic acid, an aliphatic amide, an aminoalkyl (meth) acrylate, a hydroxylated alkyl (meth) acrylate, or any combination thereof). Thus, the reactive functional group (or reactive functional groups) in each of the monomers described herein is opened or reacted during the polymerization reaction (such as, for example, a vinyl group or a hydroxyl or carbonyl group). In such a reaction, the end groups of the formed polymer are retained. Thus, the polymers of the present invention have structural repeat units of the monomeric units described herein. The polymer or graft polymer may be considered to be a polymer derived from the monomers described herein together with a polyvinyl alcohol moiety as the backbone.

The grafted polyvinyl alcohol polymer of the present invention comprises, consists essentially of, consists of, includes, or is the following: a polyvinyl alcohol backbone and a plurality of side chains grafted to the polyvinyl alcohol backbone. One or more side chains from the plurality of side chains can comprise, consist essentially of, consist of, or include: one or more units selected from aliphatic carboxylic acids, aliphatic amides, hydroxylated alkyl (meth) acrylates, and/or alkylamino (meth) acrylates, or any combination thereof.

As an explanation for the phrase "one or more side chains …," the phrase refers to the fact that: the grafted polyvinyl alcohol polymers of the invention have side chains and all, some, or one of the side chains may include, or be: aliphatic carboxylic acids, aliphatic amides, alkylamino (meth) acrylates, and/or hydroxylated alkyl (meth) acrylates. Typically, the total percentage of side chains (which include or are aliphatic carboxylic acids, aliphatic amides, alkylamino (meth) acrylates, and/or hydroxylated alkyl (meth) acrylates) is at least 10% (by number), or at least 25% (by number), or at least 50% (by number), or at least 75% (by number), or at least 85% (by number), or at least 95% (by number), for example, 10% to 100%, 30% to 90%, 30% to 80%, or 40% to 100% (all percentages being by number). When the side chain is not, or does not include, an aliphatic carboxylic acid, an aliphatic amide, an alkylamino (meth) acrylate, and/or a hydroxylated alkyl (meth) acrylate, the side chain can be an acetate moiety or an alcohol moiety.

When the side chains include or are aliphatic carboxylic acids, aliphatic amides, alkylamino (meth) acrylates, and/or hydroxylated alkyl (meth) acrylates, it is understood that one, two, three, or all four of these side chains may be present in a single side chain. Moreover, each side chain (which includes or is an aliphatic carboxylic acid, an aliphatic amide, an alkylamino (meth) acrylate, and/or a hydroxylated alkyl (meth) acrylate) can be the same or different from the other side chains. When the side chain includes an aliphatic carboxylic acid, an aliphatic amide, an alkylamino (meth) acrylate, and/or a hydroxylated alkyl (meth) acrylate, the side chain may optionally include one or more of the following substituents: hydroxypropyl methacrylate, vinyl acetate, N-vinylpyrrolidone, 4-hydroxybutyl acrylate, 2-hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxyethyl caprolactone acrylate, ethylene glycol acrylate, stearyl polyethylene glycol methacrylate, N- (3-aminopropyl) -2-acrylamide, N- (3-aminopropyl) methacrylamide hydrochloride.

As an option, one or more side chains from the plurality of side chains comprise, consist essentially of, consist of, or include: aliphatic carboxylic acid units, aliphatic amide units, and hydroxylated alkyl (meth) acrylate units. As a further option, one or more side chains from the plurality of side chains comprise, consist essentially of, consist of, or include: aliphatic carboxylic acid units, aliphatic amide units, alkylamino (meth) acrylate units, and hydroxylated alkyl (meth) acrylate units. In these examples of the grafted polyvinyl alcohol polymer of the present invention, at least one side chain has units of all three of an aliphatic carboxylic acid, an aliphatic amide, and a hydroxylated alkyl (meth) acrylate. The side chain itself may be considered a copolymer or terpolymer of these monomers.

As another option, one or more side chains from the plurality of side chains comprise, consist essentially of, consist of, or include: aliphatic carboxylic acid units; an aliphatic amide unit; a hydroxylated alkyl (meth) acrylate unit; or alkylamino (meth) acrylate units. In these examples of the grafted polyvinyl alcohol polymer of the invention, at least one side chain has only aliphatic carboxylic acid units, or only aliphatic amide units, or only hydroxylated alkyl (meth) acrylate units, or only alkylamino (meth) acrylate units. The side chain itself may be considered to be a homopolymer of the monomer used to make the side chain.

As another option, one or more side chains from the plurality of side chains can comprise, consist essentially of, consist of, or include: both aliphatic carboxylic acid units and aliphatic amide units. Alternatively, or in addition to the previous options, one or more of the side chains from the plurality of side chains may comprise, consist essentially of, consist of, or include: both aliphatic carboxylic acid units and hydroxylated alkyl (meth) acrylate units. Alternatively, or in addition to the previous options, one or more of the side chains from the plurality of side chains may comprise, consist essentially of, consist of, or include: both aliphatic amide units and hydroxylated alkyl (meth) acrylate units. Alternatively, or in addition to the previous options, one or more of the side chains from the plurality of side chains may comprise, consist essentially of, consist of, or include: both aliphatic amide units and alkylamino (meth) acrylate units. Alternatively, or in addition to the previous options, one or more of the side chains from the plurality of side chains may comprise, consist essentially of, consist of, or include: both alkylamino (meth) acrylate units and hydroxylated alkyl (meth) acrylate units. Alternatively, or in addition to the previous options, one or more of the side chains from the plurality of side chains may comprise, consist essentially of, consist of, or include: both alkylamino (meth) acrylate units and aliphatic carboxylic acid units. In each of these examples of the grafted polyvinyl alcohol polymer of the present invention, at least one side chain has units of two of an aliphatic carboxylic acid, an aliphatic amide, an alkylamino (meth) acrylate, and a hydroxylated alkyl (meth) acrylate. The side chain itself can be considered as a copolymer of the two monomers used to make the side chain.

The grafted polyvinyl alcohol polymer of the invention can have a viscosity of less than 500cP · s when present in an aqueous solution having a pH of 3 to 5 (e.g., 3) at a concentration of 22.5 to 25 wt.% at 25 ℃ and 1 atmosphere. The viscosity can be less than 300cP · s, less than 250cP · s, less than 200cP · s, less than 150cP · s, or less than 100cP · s. Viscosity is generally considered an inherent property, and thus, an aqueous solution of a polymer has a positive, non-zero viscosity value if not in a superfluid state. Therefore, the minimum value of these ranges may be 0.001 cPs, or 0.005 cPs, or 0.01 cPs, or 0.1 cPs.

Any viscometer (or viscometer) suitable for measuring the viscosity of a fluid can be used to measure the viscosity of the grafted polyvinyl alcohol polymer when in aqueous solution.

The grafted polyvinyl alcohol polymer of the invention can be dispersed in an aqueous solution at a concentration of 0.1 wt% to 40 wt% or more (e.g., 1 wt% to 40 wt%, or 5 wt% to 40 wt%, or 10 wt% to 40 wt%). All values between 10 wt.% and 40 wt.% are included within the range, inclusive. For example, the concentration of the polymer may be 12 wt% to 38 wt%, or 15 wt% to 35 wt%, or 20 wt% to 30 wt%, or 25 wt% to 28 wt%. As used herein, weight percent is defined as the weight of solute divided by the weight of solution, where the quotient is multiplied by 100%. For example, the solute is a grafted polyvinyl alcohol polymer, and the solution is the combined weight of the solute and the aqueous solvent.

The grafted polyvinyl alcohol polymer of the present invention is capable of being dispersed in an aqueous solution and forming a stable aqueous dispersion that does not exhibit coagulation or precipitation of the grafted polyvinyl alcohol polymer for a period of at least 6 months when stored at 25 ℃ and 1 atmosphere. Preferably, the stable aqueous dispersion does not exhibit coagulation or precipitation of the grafted polyvinyl alcohol polymer over a period of at least 1 year at 25 ℃ and 1 atmosphere, more preferably at least 2 years under these same conditions. As used herein, the term "coacervation" may mean the irreversible combination or aggregation of individual grafted polyvinyl alcohol polymers in an aqueous dispersion to form clumps or clumps of several or more grafted polyvinyl alcohol polymers. As used herein, the term "precipitation" may mean that the grafted polyvinyl alcohol polymer settles out of an aqueous solution under the force of gravity. The grafted polyvinyl alcohol polymer can be precipitated as an agglomeration of polymer particles.

The grafted polyvinyl alcohol polymer of the invention can be in a condensed form when present in an aqueous solution having a pH of from about 2 to about 5 or 2 to about 3 (e.g., 1.5 to 3.5, or 2 to 3.5, or 2.2 to 3, or 2.2 to 2.8, or 3 to 5, or 2 to 5, or 4 to 5, or 4.5, or 5), and can be in a semi-condensed form when present in an aqueous solution having a pH of from about 4 to about 5.5 (e.g., 3.8 to 5.8, or 4.0 to 5.5, or 4.2 to 5.2), and can be in an amorphous form when present in an aqueous solution having a pH of from about 5.5 to about 8 (e.g., 5.3 to 8.5, or 5.5 to 8.3, or 5.5 to 8.5, or 5.5 to 7.5, or 5.8 to 8, or 6.0 to 7.5). All values between the ranges of about 2 to about 5, about 2 to about 3, about 4 to about 5.5, and about 5.5 to about 8 are included in these ranges, including the endpoints of each range.

When the grafted polyvinyl alcohol polymer is in a coagulated form, the individual polymers fold upon themselves, resulting in entangled groups (entangled groups) of individual polymers clustered together to form polymer particles. By intramolecular between parts of a single polymerThe interaction occurs with folding of the individual grafted polyvinyl alcohol polymers. These intramolecular interactions may be covalent or electrostatic interactions, the most common interaction being electrostatic interaction between parts of a single polymer. For example, without wishing to be bound by a particular theory, the amide units of the grafted polyvinyl alcohol polymer may interact with the vinyl alcohol units along the polymer backbone via electrostatic interactions. In this example, the-NH groups of amide units along the polymer backbone₂The group is protonated at low pH. One example of an electrostatic interaction is van der waals interactions.

When the grafted polyvinyl alcohol polymer is in coagulated form, polymer particles can be formed in aqueous suspension. By way of example, when the polymer is an aqueous dispersion having a pH of 2, the average particle size can be 100nm to 1,000nm, 100nm to 200nm, 50nm to 150nm, and/or 150nm to 300nm, including all values within this range, as well as the decimal fractions of these values and the fractions of these values. For example, the average particle size may be about 170 nm. The particle size distribution may be multimodal, wherein, as an example, the overall average particle size is 170nm, with about 65% (by number) of the polymer particles having an average diameter of 470nm and about 25% of the polymer particles having an average diameter of 50 microns. The particle size of the polymer can be determined via dynamic light scattering experiments.

When the grafted polyvinyl alcohol polymer is in semi-coagulated form, intramolecular interactions are reduced relative to those in coagulated form, and the individual grafted polyvinyl alcohol polymers begin to unfold. However, in this form, the intramolecular interaction forces are high enough to avoid complete unfolding of the individual grafted polyvinyl alcohol polymers, and as a result, the polymer particles in coagulated form swell, causing the polymer particles in coagulated form to transform into larger size and semi-coagulated form. Although most of the individual polymers swell in size, it is also possible that some of the polymers remain in coagulated form.

When the grafted polyvinyl alcohol polymer is in a semi-coagulated form, larger, swollen polymer particles can be formed in solution. By way of example, when the polymer is an aqueous solution having a pH of 4.5, the average particle size can be 175nm to 375nm, including all values within this range, as well as the decimal fractions of these values and fractions of these values. For example, the average particle size may be about 300 nm. The particle size may be multimodal, wherein, as an example, the overall average particle size is 300nm, wherein about 95% (by number) of the polymer particles have an average diameter of 38 nm. The particle size of the polymer can be determined via dynamic light scattering experiments.

When the grafted polyvinyl alcohol polymer is in an amorphous form, the intramolecular interaction forces are sufficiently reduced that the individual polymers unfold and take a linear or substantially linear form. Although most of the individual polymers are unfolded, it is also possible that some of the polymers remain in coagulated or semi-coagulated form.

In contrast to all three forms, the coagulated form is the least soluble form of the polymer in aqueous solution and the amorphous form is the most soluble form of the polymer in aqueous solution. The amorphous form may be present, and/or have a higher population (population), and/or at a higher pH (pH alkaline conditions), and/or when the concentration of the grafted polyvinyl alcohol polymer of the invention in aqueous solution is sufficiently low (e.g., 0.1 wt% to 5 wt%).

When in aqueous solution, the grafted polyvinyl alcohol polymers of the present invention may exhibit reversible dispersibility or reversible solubility in aqueous solution. The ability to become more dispersed or more soluble and the ability to become less dispersed or less soluble can be achieved by changing the pH of the solution with the grafted polyvinyl alcohol polymer of the present invention. For example, an aqueous solution having the grafted polyvinyl alcohol polymer of the invention in coagulated form can have a pH of about 2 to about 5 or about 2 to about 3, and at that pH, the grafted polyvinyl alcohol polymer of the invention can exhibit low dispersibility or low solubility in aqueous solutions. When the pH of the aqueous solution is raised to a pH of about 5.5 to about 8 by the addition of a base to the aqueous solution, the grafted polyvinyl alcohol polymer of the present invention can be converted to an amorphous dissolved form and exhibits improved dispersibility or solubility in aqueous solutions. Thereafter, the pH of the aqueous solution can be reversibly lowered, for example, to about 2 to about 5 or about 2 to about 3, and the grafted polyvinyl alcohol polymer of the invention can revert to a coagulated form. The grafted polyvinyl alcohol polymers of the invention may again exhibit low dispersibility or solubility in aqueous solutions when returned to a coagulated form. The pH is lowered by adding an acid to an aqueous solution having the grafted polyvinyl alcohol polymer of the present invention amorphously dissolved or amorphously dispersed therein.

The pH of the aqueous solution may be raised and lowered stepwise or in a gradient by stepwise addition of a quota of a base or a quota of an acid, respectively. A quota of base or acid may be added by a dropper containing the base or acid. The base or acid is preferably an aqueous solution of the base or acid. The base can be any base described herein, and the acid can be, for example, acetic acid, hydrochloric acid, hydrobromic acid, nitric acid, and sulfuric acid. The concentration of the base or acid is not particularly limited as long as the base or acid can change the pH of the aqueous solution. For example, the concentration may be 0.01 molar to 5 molar, or 0.05 molar to 3 molar, or 0.1 to 1 molar, including any sub-values therebetween.

In the present invention, the aliphatic carboxylic acid may comprise, may consist essentially of, may consist of, may comprise, or be acrylic and/or methacrylic acid. The aliphatic amide may be an unsaturated aliphatic amide. The aliphatic amide can be a saturated aliphatic amide. The aliphatic amide can comprise, can consist essentially of, can consist of, can comprise, or be: at least one of acrylamide, methacrylamide, dimethylacrylamide, diethylacrylamide, dipropylacrylamide, and/or N-tert-butylacrylamide. The hydroxylated alkyl (meth) acrylate may comprise, may consist essentially of, may consist of, may include, or be: 2-hydroxyethyl methacrylate, hydroxypropyl methacrylate, 4-hydroxybutyl acrylate, 2-hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxyethyl caprolactone acrylate, ethylene glycol acrylate, and/or hydroxypropyl methacrylate. Additional monomers in any or all of the side chains may include vinyl acetate, N-vinyl pyrrolidone, N- (3-aminopropyl) -2-acrylamide, N-3 (aminopropyl) methacrylamide hydrochloride, and stearyl polyethylene glycol methacrylate.

In a more specific example, the aliphatic carboxylic acid is methacrylic acid; the aliphatic amide is acrylamide; and the hydroxylated alkyl (meth) acrylate is 2-hydroxyethyl methacrylate.

In the grafted polyvinyl alcohol polymer of the present invention, the grafted polyvinyl alcohol polymer can comprise, consist essentially of, consist of, or include structure (I):

-[CH₂-CH(OH)]_a-[CH₂-CH(R])]_b-(I)。

in this structure, the total weight percent of (a) units can be from 74 weight percent to 95 weight percent, based on the total weight of the grafted polyvinyl alcohol polymer. All values between 74 wt% and 95 wt% are included within the range, including the endpoints, and thus, the range may be 74 wt% to 90 wt%, 77 wt% to 92 wt%, 80 wt% to 95 wt%, 80 wt% to 92 wt%, 80 wt% to 90 wt%, 82 wt% to 95 wt%, 82 wt% to 92 wt%, or 82 wt% to 90 wt%. (b) The total weight percent of the units is from 5 weight percent to 26 weight percent, based on the total weight of the grafted polyvinyl alcohol polymer. All values between 5 wt% and 26 wt% are included within the range, including the endpoints, and thus, the range may be 5 wt% to 23 wt%, 5 wt% to 20 wt%, 8 wt% to 26 wt%, 8 wt% to 23 wt%, 8 wt% to 20 wt%, 10 wt% to 26 wt%, 10 wt% to 23 wt%, 10 wt% to 20 wt%, 12 wt% to 26 wt%, 12 wt% to 23 wt%, or 12 wt% to 20 wt%. (a) And (b) the total weight percentage of units is equal to 100%. In structure (I), R is an acetate or a side chain from multiple side chains. The plurality of units represented by structure (I) may be included in or as part of all of the grafted polyvinyl alcohol polymers of the present invention. When more than one unit of structure (I) is present, a, b, and/or R may be the same or different for each structure (I) present.

In the grafted polyvinyl alcohol polymer of the present invention, the grafted polyvinyl alcohol polymer can comprise, consist essentially of, consist of, include, or be of structure (II):

in the polymer, a may be 1 to 10 as a relative amount; b may be 35 to 55; and c may be 35 to 55 based on a + b + c being 100. All values within these ranges are inclusive; thus, a can be any one of 1, 2,3, 4,5, 6,7, 8, 9, and 10; b may be any one of 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, and 55; and c may be any one of 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, and 55, based on a + b + c being 100. A plurality of units represented by structure (II) may be included in or as part of the grafted polyvinyl alcohol polymer of the present invention. When more than one unit of structure (II) is present, a, b, and/or c may be the same or different for each structure (II) present.

The grafted polyvinyl alcohol polymer of the present invention may be a polymer that exhibits or possesses one or more of the following properties: a) the grafted polyvinyl alcohol polymer is a latex; b) the grafted polyvinyl alcohol polymer is capable of being completely dispersed in water in an amount of 1 to 25 wt% at a pH of 2-5 or 2-3; c) the grafted polyvinyl alcohol polymer is not an irreversible gel at any pH; and/or d) the grafted polyvinyl alcohol polymer is gel-free at a pH of 8.

The grafted polyvinyl alcohol polymers of the present invention may exhibit one or more glass transition temperatures. For example, the grafted polyvinyl alcohol polymer has a first glass transition temperature of-40 ℃ to 60 ℃ or 40 ℃ to 60 ℃, and a second glass transition temperature of 70 ℃ to 90 ℃. The glass transition temperature may be any value within these ranges. For example, the first glass transition temperature can be from-40 ℃ to 50 ℃, or from-40 ℃ to 40 ℃, or from-40 ℃ to 30 ℃, or from-40 ℃ to 20 ℃, or from-30 ℃ to 60 ℃, or from-20 ℃ to 60 ℃, or from-10 ℃ to 60 ℃, or from 0 ℃ to 60 ℃, or from 10 ℃ to 60 ℃, or from 20 ℃ to 60 ℃, or from 30 ℃ to 60 ℃, or from 40 ℃, 41 ℃, 42 ℃,43 ℃,44 ℃, 45 ℃,46 ℃, 47 ℃,48 ℃,49 ℃,50 ℃, 51 ℃,52 ℃, 53 ℃,54 ℃, 55 ℃,56 ℃,57 ℃, 58 ℃, 59 ℃, or 60 ℃. The second glass transition temperature can be 70 ℃,71 ℃, 72 ℃, 73 ℃,74 ℃, 75 ℃,76 ℃,77 ℃,78 ℃,79 ℃, 80 ℃,81 ℃, 82 ℃,83 ℃,84 ℃, 85 ℃,86 ℃,87 ℃,88 ℃,89 ℃, or 90 ℃. These numbers may be taken as the minimum or maximum of a subrange having a broader range.

Without wishing to be bound by a particular theory, the first glass transition temperature is the glass transition temperature of one or more side chains grafted to the polyvinyl alcohol backbone, and the second glass transition temperature is the glass transition temperature of the polyvinyl alcohol backbone. Any method and/or technique suitable for measuring glass transition temperature can be used to measure the glass transition temperature of the grafted polyvinyl alcohol polymer of the present invention. As an example, the glass transition temperature can be measured using a dynamic mechanical thermal analysis rheometer.

Other properties of the grafted polyvinyl alcohol polymer of the present invention include the weight average molecular weight and the number average molecular weight of the grafted polyvinyl alcohol polymer. For example, the grafted polyvinyl alcohol polymer of the invention can have a weight average molecular weight of about 50,000 daltons to about 1,500,000 daltons (e.g., 100,000 daltons to 1,000,000 daltons, or 250,000 daltons to 750,000 daltons). The grafted polyvinyl alcohol polymer of the present invention can have a number average molecular weight of from 2,000 daltons to about 50,000 daltons. The weight average molecular weight and number average molecular weight of the grafted polyvinyl alcohol polymer can be measured by gel permeation chromatography.

The polydispersity of a polymer is generally defined as the weight average molecular weight of the polymer divided by the number average molecular weight of the polymer (PD ═ Mw/Mn). The grafted polyvinyl alcohol polymer of the invention can have a polydispersity Mw/Mn of at least 1.5.

As indicated by the two glass transition temperatures in an exemplary grafted polyvinyl alcohol of the present invention, the backbone of the polymer, when in free, unreacted form, may have the property characteristics of the backbone itself. For example, the polyvinyl alcohol backbone in an unreacted form may have a molecular weight distribution of from about 5,000 daltons to about 1,000,000 daltons before grafting the monomers onto the backbone. In this example, the molecular weight distribution of the polyvinyl alcohol backbone in free, unreacted form is a monomodal, bimodal, or multimodal molecular weight distribution. The polyvinyl alcohol backbone in free, unreacted form can have a weight average molecular weight of from 2,000 daltons to 500,000 daltons, and/or, can have a number average molecular weight of from about 1,000 daltons to about 50,000 daltons. Thus, the polyvinyl alcohol backbone in free, unreacted form can have a polydispersity Mw/Mn of from 2 to 7.

Further, the polyvinyl alcohol backbone in free, unreacted form may have a degree of hydrolysis of from about 74 mole% to about 98 mole%, or other amounts below or above this range. All values between 74 mol% and 98 wt% are included within the range, including the endpoints, and thus, the range may be 74 mol% to 95 mol%, 74 mol% to 90 mol%, 74 mol% to 88 mol%, 76 mol% to 95 mol%, 76 mol% to 90 mol%, and 76 mol% to 88 mol%. As all values between 74 mol% and 98 wt% are included within this range, the degree of hydrolysis may be 74 mol%, 75 mol%, 76 mol%, 77 mol%, 78 mol%, 79 mol%, 80 mol%, 81 mol%, 82 mol%, 83 mol%, 84 mol%, 85 mol%, 86 mol%, 87 mol%, 88 mol%, 89 mol%, 90 mol%, 91 mol%, 92 mol%, 93 mol%, 94 mol%, 95 mol%, 96 mol%, 97 mol%, and 98 mol%, including fractions and fractions thereof.

The degree of hydrolysis can be an indicator of how many free alcohol moieties (-OH) are present on the backbone of the polyvinyl alcohol backbone. The synthesis of polyvinyl alcohol involves first the polymerization of vinyl acetate, which forms polyvinyl acetate. Thereafter, the acetate moiety (-O- (CO) -CH)₃) Is partially replaced by alcohol via a hydrolysis reaction. Thus, as used herein, "degree of hydrolysis" may refer to the mole% of acetate moieties replaced by alcohol moieties when polyvinyl acetate is transesterified. Thus, as an example, for a polyvinyl alcohol backbone characterized by a degree of hydrolysis of 74 mole%, 74 mole% of the acetate moieties are replaced with alcohol moieties.

The unreacted form of the polyvinyl alcohol backbone can be: POVAL^TM(Kurary co., Ltd.)5/88, 3/80, 3/82, 3/85, 4/85, 4/88, 5/82, 6/88, 13/88, 3/88, 5/74, 5/88, 8/88, and RS 2117; selvol^TM(Sekisui Specialty Chemicals America, LLC)5002, 513, 518, 418, 425, 443, 203, 523, 205, and 540; and any combination thereof.

Another aspect and feature of the present invention relates to a formulation that may comprise, may consist of, may consist essentially of, may include, or be: an aqueous phase and the grafted polyvinyl alcohol polymer of the invention. In one aspect, the formulation may comprise, may consist of, may consist essentially of, or may include the following: 100 parts by weight of an aqueous phase and 1 to 40 parts by weight or more (e.g., 10 to 40 parts by weight) of the grafted polyvinyl alcohol polymer of the present invention, wherein in the formulation, the grafted polyvinyl alcohol polymer is dispersed in the aqueous phase. All values between 1 and 40 parts by weight are included within the range, including the endpoints, and thus, the range may be 5 to 35 parts by weight, 10 to 30 parts by weight, 12 to 40 parts by weight, 12 to 38 parts by weight, 12 to 35 parts by weight, 14 to 40 parts by weight, 14 to 35 parts by weight, 15 to 40 parts by weight, 15 to 38 parts by weight, and 15 to 35 parts by weight. Since all numerical values between 1 part by weight and 40 parts by weight are included in the range, the parts by weight may be, for example, 2 parts by weight, 5 parts by weight, 10 parts by weight, 11 parts by weight, 12 parts by weight, 13 parts by weight, 14 parts by weight, 15 parts by weight, 16 parts by weight, 17 parts by weight, 18 parts by weight, 19 parts by weight, 20 parts by weight, 21 parts by weight, 22 parts by weight, 23 parts by weight, 24 parts by weight, 25 parts by weight, 26 parts by weight, 27 parts by weight, 28 parts by weight, 29 parts by weight, 30 parts by weight, 31 parts by weight, 32 parts by weight, 33 parts by weight, 34 parts by weight, 35 parts by weight, 36 parts by weight, 37 parts by weight, 38 parts by weight, 39 parts by weight, and 40 parts by weight, including decimal parts and fractions thereof.

The formulations of the present invention may be stable aqueous dispersions that do not exhibit coagulation or precipitation of the grafted polyvinyl alcohol polymer during storage at 25 ℃ and 1 atmosphere for a period of at least 6 months. Alternatively, the aqueous dispersion is stable for a period of at least 1 year, or for a period of at least 2 years, when stored at 25 ℃ and 1 atmosphere. The terms "agglomeration" and "precipitation" herein have the same definitions as given above.

The formulations of the present invention can have a pH of from about 2 to about 5 or from about 2 to about 3, and when the formulation has such a pH, the grafted polyvinyl alcohol polymer can be in a coagulated form as previously discussed. As another option, the formulations of the present invention can have a pH of about 4 to about 5.5, and when the formulation has that pH, the grafted polyvinyl alcohol polymer is in a semi-coagulated form as previously discussed. As a further option, the formulation of the present invention may have a pH of about 5.5 to about 8, and when the formulation has that pH, the grafted polyvinyl alcohol polymer is in an amorphous dissolved form as previously discussed.

In the formulations of the present invention, the grafted polyvinyl alcohol polymer may be dissolved in the aqueous phase of the formulation in an amount of at least 10g/100g water. As an option, the maximum amount of grafted polyvinyl alcohol polymer in the formulations of the present invention may be about 50g/100g of water or higher. Other ranges within these extremes are also possible, such as: 10g/100g water-45 g/100g water; 12g/100g water-45 g/100g water; 15g/100g water-45 g/100g water; 15g/100g water-40 g/100g water; 18g/100g water-45 g/100g water; 18g/100g water-40 g/100g water; 20g/100g water-45 g/100g water; 20g/100g water-40 g/100g water. All values within these ranges are useful, for example: 10. 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, and 50, or fractions thereof.

At these concentrations of polymer in water, the formulations of the present invention can be highly concentrated products, which reduces the volume for shipping and storage. Because the grafted polyvinyl alcohol polymer can be dispersed or dissolved in aqueous solution without gelling or other viscosity problems, formulations with higher concentrations of grafted polyvinyl alcohol polymer can exist, especially as compared to conventional polyvinyl alcohols. The end user of the concentrated product (e.g., a paper company or other user) may dilute the concentrate to the solids content required for the application, or alternatively, may pump or otherwise transfer directly into the Yankee or rotary drum boom coating solution.

In addition to the aqueous phase and the grafted polyvinyl alcohol polymer, the formulations of the present invention may also include at least one plasticizer. The plasticizer may be at least one of: glycerol, propylene glycol, 2-oxopropylene dibenzoate, 3-dipropylene glycol dibenzoate, and 4-diethylene glycol dibenzoate. If present, the plasticizer may be present in an amount of 1 to 15% by weight, relative to 100% by weight of the dispersion. For example, if glycerin is present, it may be present in an amount of 1 to 15% by weight, relative to 100% by weight of the dispersion. If 2-oxopropyl dibenzoate, it may be present in an amount of from 1 to 5% by weight, relative to 100% by weight of the dispersion. If present, 3-dipropylene glycol dibenzoate may be present in an amount of 1 to 5 wt.%, relative to 100 wt.% of the dispersion. If 4-diethylene glycol dibenzoate is present, it may be present in an amount of from 1 to 5% by weight, relative to 100% by weight of the dispersion. If present, propylene glycol may be present in an amount of 1 to 5% by weight, relative to 100% by weight of the dispersion.

In addition to the aqueous phase and the grafted polyvinyl alcohol polymer, the formulations of the present invention may include one or more surfactants or no surfactants. Although no surfactant is required in the formulations of the present invention, it can be present in any conventional amount. Since a surfactant is not necessary, the amount of surfactant can be less than 1 wt% surfactant (e.g., 0 wt% to 0.9 wt%, 0.001 wt% to 0.5 wt%, 0.001 wt% to 0.1 wt%). The formulations of the present invention may be surfactant-free or, alternatively, surfactant-free. If present, the surfactant can be at least one of a cationic surfactant, an anionic surfactant, and/or a nonionic surfactant.

Examples of surfactants include, but are not limited to, cetyl trimethylammonium bromide, sodium lauryl sulfate, and/or condensation products of alkylene oxides (e.g., Ethylene Oxide (EO)) with hydrophobic molecules. Examples of hydrophobic molecules include fatty alcohols, fatty acids, fatty acid esters, triglycerides, fatty amines, fatty amides, alkyl phenols, polyols, and partial fatty acid esters thereof. Other examples include polyalkylene oxide block copolymers, ethylene diamine tetra block copolymers of polyalkylene oxides, and alkyl polyglycosides. Examples include nonionic surfactants that are ethoxylates of fatty alcohols, wherein the alcohol is about C₁₀-C₁₈Branched or linear, for example SURFONIC L (Huntsman Corporation, Houston, Tex.) or TDA series, NEODOL (Shell Chemical Company, Houston, Tex.) series, and TERGITOL series (Union Carbide Corporation, Danbury Conn.). Other examples of nonionic surfactants include alkylphenol ethoxylates, polyethylene glycol esters of long chain fatty acidsEthoxylated fatty amines, polymers comprising ethylene oxide and propylene oxide blocks, and alkyl polyglycosides.

The surfactant (e.g., a polymeric surfactant) can have an average molecular weight (in daltons) of 1,000 to about 20,000, for example, about 2,000 to about 15,000, about 3,000 to about 12,000, about 5,000 to about 20,000, about 10,000 to about 20,000, about 12,000 to about 17,000, about 13,500 to about 16,000, at least about 20,000, at least about 50,000, at least about 100,000, or at least about 500,000.

Another aspect of the invention is a method of making a grafted polyvinyl alcohol polymer according to the invention. The method can comprise, consist essentially of, consist of, comprise, or be a step of: at least one of an aliphatic carboxylic acid, an aliphatic amide, and/or a hydroxylated alkyl (meth) acrylate is polymerized via free radical polymerization in the presence of free polyvinyl alcohol.

The method may comprise, consist essentially of, consist of, comprise, or have the following steps: adding at least one of an aliphatic carboxylic acid, an aliphatic amide, an alkylamino (meth) acrylate, and a hydroxylated alkyl (meth) acrylate, or mixing together at least one of an aliphatic carboxylic acid, an aliphatic amide, an alkylamino (meth) acrylate, and a hydroxylated alkyl (meth) acrylate (the aqueous solution comprising, consisting essentially of, consisting of, or comprising water and a polyvinyl alcohol polymer) to an aqueous solution to obtain an aqueous solution of monomers and free PVOH. The adding or mixing step can be performed for at least 15 minutes or more, for example, 15 minutes to 2 hours or more. The polymerization step is initiated by adding an initiator (e.g., ammonium persulfate, sodium bisulfite, hydrogen peroxide, and t-butyl hydroperoxide) to an aqueous solution of the monomers and free PVOH.

Alternatively, the method may comprise, consist essentially of, consist of, comprise, or have the following steps: the monomer is added stepwise or semi-continuously to the reactor at a temperature of from 35 ℃ to 80 ℃. The reactor may contain the polyvinyl alcohol backbone in unreacted form prior to the step-wise or semi-continuous addition of the monomers to the reactor. The temperature range may be, for example, 40 ℃ to 70 ℃, and preferably 65 ℃. The method can further comprise, consist essentially of, consist of, include, or have the steps of: polymerization is carried out by adding an initiator (e.g., ammonium persulfate, hydrogen peroxide, and t-butyl hydroperoxide) to an aqueous solution of the mixture of monomer and free PVOH. Sodium bisulfite may be included as part of the initiator, and, without wishing to be bound by a particular theory, is believed to reduce the dissociation temperature of any peroxide present in the initiator, thereby reducing the energy costs associated with initiating polymerization.

The initiator may be added all at once at the beginning of the polymerization, or may be added over time (e.g., dropwise and over a period of time). If dropwise, the time period for dropwise semi-continuous addition of monomer may be 15 minutes to 5 hours or more, 30 minutes to 3 hours, or 45 minutes to 2 hours.

Upon addition of all or a portion of the initiator, an aqueous solution of monomer and free PVOH can be considered a reaction solution, and graft polymerization of the monomer can be carried out in the reaction solution. The temperature of the reaction solution during polymerization may be from 30 ℃ to 100 ℃, for example from 30 ℃ to 85 ℃, with all numbers and values being included in this range.

The method may further comprise, consist essentially of, consist of, comprise, or have the step of terminating the polymerization step. Termination of the polymerization can occur by addition of hydroquinone to the reaction solution.

An interesting aspect of the present invention is that the graft polymerization of the monomers in the present invention can be carried out entirely using acrylic monomers. In other words, the graft polymerization may be carried out in the substantial absence or complete absence of an ethylene-based monomer. With the present invention, the percentage of the acrylic monomer used in the graft polymerization may be, for example, 50% (by number) or more, for example, 50% (by number) to 100% (by number), or 75% (by number) to 99% (by number), or 85% (by number) to 98% (by number), based on the total number of graft sites on the polyvinyl alcohol main chain. The vinylic monomer may be present in an amount of 0, or less than 5%, or less than 3%, or less than 1%, or less than 0.5%, or less than 0.1% (by number) based on the total number of grafting sites on the polyvinyl alcohol backbone.

Another aspect of the invention is a method of making an aqueous solution of the grafted polyvinyl alcohol polymer according to the invention. The method can comprise, consist essentially of, consist of, comprise, or be a step of: a base is added to the dispersion to raise the pH of the dispersion to 4 to 8 (e.g., from above 5 to 8) and form an aqueous solution of the grafted polyvinyl alcohol polymer. In the method, the dispersion can comprise, consist essentially of, consist of, include, or be: an aqueous phase and a grafted polyvinyl alcohol polymer dispersed in the aqueous phase. The dispersion may have a pH of 2 to 5 or 2 to 3 prior to the step of adding a base to the dispersion.

The base can be any compound or composition that has a basic pH and is capable of raising the pH of the dispersion. Examples of alkalis include, but are not limited to, caustic, alkaline (e.g., alkali metal, alkaline earth metal), and alkaline buffer, or any combination thereof. The base may be inorganic or organic, or a combination or mixture of these different types of basic materials. The base may be, for example, an alkali metal hydroxide, an alkali metal oxide, an alkali metal phosphate, an alkali metal carbonate, an alkali metal bicarbonate, an alkaline earth metal hydroxide, an alkaline earth metal oxide, an alkaline earth metal phosphate, an alkaline earth metal carbonate, ammonium zirconium carbonate, an organotitanate, an organozirconate, ammonium hydroxide, ammonium carbonate, ammonium bicarbonate, an alkali metal silicate, urea, substituted urea, cyanate, alkylamine, alkanolamine, quaternary ammoniumSalts, salts of weak acids with strong bases, basic buffer solutions, polyalkali metal pyrophosphates, or any combination thereof. An example of an alkali metal hydroxide that can be used is NaOH. Alkali salts (alkali metal salts) can be used as brine or in the form of water-soluble salts. As an option, alkaline buffering agents may be used in the adhesive base formulation to establish alkalinity and resist pH changes. Examples of alkaline buffers that can be used include, for example, magnesium oxide, and aqueous solutions of disodium phosphate and monosodium phosphate. Examples of alkanolamines include triethanolamine, diethanolamine, or monoethanolamine. The base can be, for example, an Arrhenius base (i.e., a material that ionizes in water to produce hydroxide ions), a Bronsted-Lowry base (i.e., a base that can accept protons or hydrogen cations (H)⁺) Of (b) or lewis base (i.e., species that donate an electron pair) so long as its introduction is capable of affecting an increase in the pH of the binder base formulation.

The dose rate of the base (dosage rate) depends on the following factors: the level of pH increase sought, the alkali strength of the particular material, and the rate of addition. As a non-limiting example, to raise the pH of the dispersion by about 0.5 units, a 10 wt% NaOH solution can be added to a dispersion having an original pH of about 4.0 to about 6.0 in water in an amount ranging from about 1/30 to about 30/1 (e.g., 1/10, or 10/1, or other range values) in a weight to weight ratio (solids only). The magnitude of the further increase in pH obtained by further increasing the amount of base added may be approximately proportional, or at least may tend to be correlated (trend together).

As an alternative to the addition of a base, the aqueous dispersion may be diluted with water to increase the pH. The transition of the grafted polyvinyl alcohol polymer in the aqueous dispersion from the coagulated form, to the semi-coagulated form, to the amorphous dissolved form may be carried out while adding water to the low pH aqueous dispersion.

The invention further relates to a creping process comprising using the formulation of the invention as a creping adhesive. For example, a process for creping a fibrous web may comprise: a rotating cylindrical dryer or similar roll is provided that includes a dryer surface. Applying a binder formulation comprising the formulation of the present invention to a dryer surface, and conveying the fibrous web to the dryer surface. On the dryer surface, the fiber web is dried to form a dried fiber web, and the dried fiber web is creped from the dryer surface. As an option, the fibrous web to be creped may be through-air dried before being transferred to the Yankee dryer surface that has been pre-coated with the improved creping adhesive formulation.

As an option, the adhesive formulation is a dispersion as described herein. During the creping process of the present invention, the formulation may have a pH of about 4.5 to about 6 and the grafted polyvinyl alcohol polymer may be dissolved in the dispersion amorphously. The formulation may have the grafted polyvinyl alcohol polymer present at a concentration of 0.1 to 5 wt% (e.g., about 0.5 to 3 wt%, or other amounts), all based on the total weight of the adhesive formulation.

The creping process may further comprise, consist essentially of, or comprise the steps of: substantially removing the formulation from the wrinkled dryer surface. Prior to this substantial removal of the formulation from the drying surface, the pH of the formulation on the dryer surface may be raised to a pH above 6, which may facilitate the removal of the formulation from the dryer surface.

The formulation may be applied to a Yankee dryer or other cylindrical dryer used in such creping processes. The formulation can be applied to the cylindrical dryer surface on a continuous basis, a semi-continuous basis, an intermittent basis, or a disposable basis prior to, during, or both prior to and during rotation. The formulations of the invention may be applied as follows: to the surface of a cylindrical dryer (e.g., after the creping blade and before the web transfer location); before or during application of the fiber web to the cylindrical dryer surface and/or after application of the fiber web to the cylindrical dryer surfaceThe web. The formulation may be applied by using one or more nozzles of a spray boom, roll coater, dip bath for the fiber web, or other coating device. The application or application rate of the adhesive formulation may be 0.1mg/m²The surface of the dryer is 40mg/m²Surface of dryer, for example, 0.1mg/m²The surface of the dryer is up to 20mg/m²Surface of dryer, or 0.1mg/m²Surface of dryer to 10mg/m²Surface of dryer, or 1mg/m²Surface of dryer to 10mg/m²Surface of dryer, or 5mg/m²Surface of dryer to 10mg/m²Dryer surface, or other quantities.

Creping systems, methods, and adhesives are described in the following U.S. patents (the entire contents of which are incorporated herein by reference): 3,640,841, respectively; 4,304,625, respectively; 4,440,898, respectively; 4,788,243, respectively; 4,994,146, respectively; 5,025,046, respectively; 5,187,219; 5,326,434, respectively; 5,246,544, respectively; 5,370,773, respectively; 5,487,813, respectively; 5,490,903, respectively; 5,633,309, respectively; 5,660,687; 5,846,380, respectively; 4,300,981; 4,063,995, respectively; 4,501,640, respectively; 4,528,316; 4,886,579, respectively; 5,179,150; 5,234,547, respectively; 5,374,334; 5,382,323; 5,468,796, respectively; 5,902,862, respectively; 5,942,085, respectively; 5,944,954, respectively; 3,301,746, respectively; 3,879,257, respectively; 4,684,439, respectively; 3,926,716, respectively; 4,883,564, respectively; and 5,437,766.

The adhesive formulations of the present invention may be used in other applications in the papermaking industry or other industries. The adhesive formulations of the present invention may be considered biodegradable, and/or non-toxic, and/or contain one or more food grade ingredients.

The invention will be further elucidated by the following examples, which are intended as illustrations of the invention.

Examples

Example 1 Synthesis of Polymer 1

The resin is prepared by dissolving a polyvinyl alcohol polymer in water. Methacrylic acid, acrylamide, and 2-hydroxyethyl methacrylate are mixed in an aqueous PVOH solution for at least 30 minutes to form a precursor solution.

The batch polymerization was initiated by adding a solution of ammonium persulfate initiator to the precursor solution at 60 ℃ and the polymerization was carried out at 80 ℃ for 2 hours. Ammonium persulfate was held at 80 ℃ for 120 minutes at a constant feed rate. The residual monomer was quenched by t-butyl hydroperoxide and hydrogen peroxide at 40 ℃ for 30 minutes. Table 1 shows the reactants and relative amounts in this polymerization.

TABLE 1 graft copolymerization formulation for Polymer 1

Polymer 1 was analyzed using gel permeation chromatography ("GPC"). A GPC trace was obtained, and from this GPC trace, the weight average and number average molecular weights of polymer 1 were obtained. The weight average molecular weight of polymer 1 was 194,831 daltons, and the number average molecular weight of polymer 1 was 25,790 daltons. The polydispersity index value Mw/Mn of polymer 1 is 7.74.

Polymer 1 was dispersed in the aqueous phase of the aqueous formulation and the pH of the formulation was adjusted to 2. The pH adjustment was performed by adding a 10% aqueous sodium hydroxide solution to the formulation. The formulation was analyzed using dynamic light scattering to determine the polymer particle size distribution at the pH. The polymer was found to have an average particle size of 170nm, with 66.1 volume percent of the particles having an average diameter of 470nm and 24 volume percent of the particles having an average diameter of 50 microns.

The pH of the formulation was raised to 4.5 by adding a base to the formulation at pH 2, and the formulation at pH 4.5 was analyzed using dynamic light scattering to determine the polymer particle size distribution at that pH. The polymer was found to have an average particle size of 300nm, with 95 volume percent of the particles having an average diameter of 380 nm.

Example 2 testing with Polymer 1

A test method was developed in which after heating at 100 ℃ for 15 seconds, the nonwoven fabric was laminated with the polymer solution and then the nonwoven fabric was dried at different time intervals of 15, 30 and 60 seconds. For each time interval, the peel force was measured separately and independently. A 15 second measurement is defined as the pick-up (pick-up) adhesion value when the polymer film is still wet, a 30 second measurement is the holding capacity of the semi-dry film to the semi-dry tissue substrate, and finally, a 60 second measurement is the adhesion between the dry tissue and the dry film when they encounter the creping blade; the setting (acceptance) is the drying curve over a hot stainless steel plate at 100 ℃ based on 0.8ml of a 2.5% polymer solution.

Table 2: adhesion Capacity of Polymer 1 compared to other Polymer compositions

Example 3 particle size analysis of Polymer 1 in aqueous media at different pH

At pH 2, an aqueous dispersion of polymer 1 was obtained. As the pH was increased from 2 to 4.5, the average particle size increased from 170nm to 300nm, as shown in Table 3 below. This increase may be due to water swelling of the particles caused by the carboxyl, hydroxyl and amide groups of the polymer. At pH 4.5, 95% of the particle groups had an average diameter of 380nm, and, due to water swelling, the polydispersity index dropped from 0.61 at pH 2 to 0.39 at pH 4.5.

The pH was further raised to 6, which significantly reduced the average particle diameter to 80nm as a result of the transition from the colloidal particle state to a stretched, free-flowing amorphous polymer. The polydispersity index at pH 6 increased to 0.8; this broad polydispersity is attributed to the complete breakdown of the coagulated particles into unfolded, fully hydrated polymer. At pH 2, the particles as well as free PVOH particles are forced to shrink due to the increased level of intramolecular attraction, and therefore 72% of the volume weighted particles have an average diameter of 29 nm. At pH 4.5, the level of intra-molecular physical attraction as well as the level of inter-particle physical attraction decreased, supporting the discovery that 88% of the particles had an increased average diameter of 500 nm. When the particles were converted to solution or spread at pH 6, 99.8% of the particles had an average diameter of only 6nm, which indicates that the polymer dispersion was converted between particles and free hydrocolloid (hydrocoloidal) molecules.

Table 3: particle size of Polymer 1 at different pH

The invention comprises the following aspects/embodiments/features in any order and/or in any combination:

1. a grafted polyvinyl alcohol polymer comprising a polyvinyl alcohol backbone and a plurality of side chains grafted to the polyvinyl alcohol backbone,

wherein one or more of said side chains from the plurality of side chains comprises one or more units selected from: an aliphatic carboxylic acid, an aliphatic amide, a hydroxylated alkyl (meth) acrylate, an alkylamino (meth) acrylate, or any combination thereof.

2. The grafted polyvinyl alcohol polymer of any preceding or subsequent embodiment/feature/aspect, wherein one or more of the side chains from the plurality of side chains comprises: aliphatic carboxylic acid units, aliphatic amide units, and hydroxylated alkyl (meth) acrylate units.

3. The grafted polyvinyl alcohol polymer of any preceding or subsequent embodiment/feature/aspect, wherein one or more of the side chains from the plurality of side chains comprises an aliphatic carboxylic acid unit.

4. The grafted polyvinyl alcohol polymer of any preceding or subsequent embodiment/feature/aspect, wherein one or more of the side chains from the plurality of side chains comprises an aliphatic amide unit.

5. The grafted polyvinyl alcohol polymer of any preceding or subsequent embodiment/feature/aspect, wherein one or more of the side chains from the plurality of side chains comprises a hydroxylated alkyl (meth) acrylate unit.

6. The grafted polyvinyl alcohol polymer of any preceding or subsequent embodiment/feature/aspect, wherein one or more of the side chains from the plurality of side chains comprises alkylamino (meth) acrylate units.

7. The grafted polyvinyl alcohol polymer of any preceding or subsequent embodiment/feature/aspect, wherein one or more of the side chains from the plurality of side chains comprises: aliphatic carboxylic acid units and aliphatic amide units.

8. The grafted polyvinyl alcohol polymer of any preceding or subsequent embodiment/feature/aspect, wherein one or more of the side chains from the plurality of side chains comprises: aliphatic carboxylic acid units and hydroxylated alkyl (meth) acrylate units.

9. The grafted polyvinyl alcohol polymer of any preceding or subsequent embodiment/feature/aspect, wherein one or more of the side chains from the plurality of side chains comprises: aliphatic amide units and hydroxylated alkyl (meth) acrylate units.

10. The grafted polyvinyl alcohol polymer of any preceding or subsequent embodiment/feature/aspect, wherein one or more of the side chains from the plurality of side chains comprises: aliphatic amide units and alkylamino (meth) acrylate units.

11. The grafted polyvinyl alcohol polymer of any preceding or subsequent embodiment/feature/aspect, wherein the grafted polyvinyl alcohol polymer has a viscosity of less than 500cP · s when present at a concentration of 22.5 to 25 wt.% in an aqueous dispersion having a pH of 3 at 25 ℃ and 1 atmosphere.

12. The grafted polyvinyl alcohol polymer of any preceding or subsequent embodiment/feature/aspect, wherein the grafted polyvinyl alcohol polymer has a viscosity of less than 100cP · s when present at a concentration of 2.5 to 10 wt.% in an aqueous solution having a pH of 3 at 25 ℃ and 1 atmosphere.

13. The grafted polyvinyl alcohol polymer of any preceding or subsequent embodiment/feature/aspect, wherein the grafted polyvinyl alcohol polymer is dispersible in the aqueous solution at a concentration of 10 wt% to 40 wt%.

14. The grafted polyvinyl alcohol polymer of any preceding or subsequent embodiment/feature/aspect, wherein the grafted polyvinyl alcohol polymer is capable of being dispersed in an aqueous solution and forming a stable aqueous dispersion that does not exhibit coagulation or precipitation of the grafted polyvinyl alcohol polymer over a period of at least 6 months at 25 ℃ and 1 atmosphere.

15. The grafted polyvinyl alcohol polymer of any preceding or subsequent embodiment/feature/aspect, wherein the grafted polyvinyl alcohol polymer is capable of being in a coagulated form when present in an aqueous solution having a pH of about 2 to about 5 or about 2 to about 3, is capable of being in a semi-coagulated form when present in an aqueous solution having a pH of about 4 to about 5.5, and is capable of being in an amorphous form when present in an aqueous solution having a pH of about 5.5 to about 8.

16. The grafted polyvinyl alcohol polymer of any preceding or subsequent embodiment/feature/aspect, wherein the grafted polyvinyl alcohol polymer has one or more of the following properties:

a) the grafted polyvinyl alcohol polymer is a latex;

b) the grafted polyvinyl alcohol polymer is capable of being completely dispersed in water in an amount of 1 to 25 wt% at a pH of 2-3 or a pH of 2-5;

c) the grafted polyvinyl alcohol polymer is not an irreversible gel at any pH; and

d) the grafted polyvinyl alcohol polymer is gel-free at a pH of 8.

17. The grafted polyvinyl alcohol polymer of any preceding or subsequent embodiment/feature/aspect, wherein the grafted polyvinyl alcohol polymer has a first glass transition temperature of-40 ℃ to 60 ℃ and a second glass transition temperature of 70 ℃ to 90 ℃.

18. The grafted polyvinyl alcohol polymer of any preceding or subsequent embodiment/feature/aspect, wherein the grafted polyvinyl alcohol polymer has a weight average molecular weight of 5,000 daltons to about 1,500,000 daltons.

19. The grafted polyvinyl alcohol polymer of any preceding or subsequent embodiment/feature/aspect, wherein the grafted polyvinyl alcohol polymer has a number average molecular weight of from 1,000 daltons to about 50,000 daltons.

20. The grafted polyvinyl alcohol polymer of any preceding or subsequent embodiment/feature/aspect, wherein the grafted polyvinyl alcohol polymer has a polydispersity Mw/Mn of at least 1.5.

21. The grafted polyvinyl alcohol polymer of any preceding or subsequent embodiment/feature/aspect, wherein the polyvinyl alcohol backbone in unreacted form has a weight average molecular weight of from about 5,000 daltons to about 1,500,000 daltons.

22. The grafted polyvinyl alcohol polymer of any preceding or subsequent embodiment/feature/aspect, wherein the molecular weight distribution is a monomodal, bimodal, or multimodal molecular weight distribution.

23. The grafted polyvinyl alcohol polymer of any preceding or subsequent embodiment/feature/aspect, wherein the polyvinyl alcohol backbone in unreacted form has a number average molecular weight of from about 1,000 daltons to about 50,000 daltons.

24. The grafted polyvinyl alcohol polymer of any preceding or subsequent embodiment/feature/aspect, wherein the polyvinyl alcohol backbone in unreacted form has a polydispersity Mw/Mn of 2 to 7.

25. The grafted polyvinyl alcohol polymer of any preceding or subsequent embodiment/feature/aspect, wherein the polyvinyl alcohol backbone has a degree of hydrolysis of from about 74 mol% to about 95 mol%.

26. The grafted polyvinyl alcohol polymer of any preceding or subsequent embodiment/feature/aspect,

wherein an aliphatic carboxylic acid is present and comprises at least one of acrylic acid and methacrylic acid,

wherein an aliphatic amide is present and comprises at least one of acrylamide, methacrylamide, dimethylacrylamide, diethylacrylamide, dipropylacrylamide and N-tert-butylacrylamide, and

wherein the hydroxylated alkyl (meth) acrylate is present and comprises at least one of 2-hydroxyethyl methacrylate and hydroxypropyl methacrylate.

27. The grafted polyvinyl alcohol polymer of any preceding or subsequent embodiment/feature/aspect,

wherein alkylamino (meth) acrylate is present and is or comprises N- (3-aminopropyl) -2-acrylamide and/or N- (3-aminopropyl) methacrylamide hydrochloride.

28. The grafted polyvinyl alcohol polymer of any preceding or subsequent embodiment/feature/aspect,

wherein the aliphatic carboxylic acid is present and is methacrylic acid,

wherein an aliphatic amide is present and is acrylamide, and

wherein the hydroxylated alkyl (meth) acrylate is present and is 2-hydroxyethyl methacrylate.

29. The grafted polyvinyl alcohol polymer of any preceding or subsequent embodiment/feature/aspect, comprising structure (I):

-[CH₂-CH(OH)]_a-[CH₂-CH(R])]_b-(I)

wherein the total weight percent of (a) units is from 74% to 95% based on the total weight of the grafted polyvinyl alcohol polymer,

wherein the total weight percent of (b) units is from 5% to 26%, based on the total weight of the grafted polyvinyl alcohol polymer,

wherein each R is an acetate or a side chain from the plurality of side chains.

30. The grafted polyvinyl alcohol polymer of any preceding or subsequent embodiment/feature/aspect, comprising structure (II):

wherein a is 1 to 10; b is 35 to 55; c is 35 to 55, provided that a + b + c is 100.

31. A formulation comprising:

an aqueous phase; and

the grafted polyvinyl alcohol polymer of any preceding or subsequent embodiment/feature/aspect.

32. The formulation of any preceding or subsequent embodiment/feature/aspect, wherein the formulation comprises:

100 parts by weight of an aqueous phase; and

10 to 40 parts by weight of a grafted polyvinyl alcohol polymer, wherein

The grafted polyvinyl alcohol polymer is dispersed in the aqueous phase.

33. The formulation of any preceding or subsequent embodiment/feature/aspect, wherein the formulation is a stable aqueous dispersion that does not exhibit coagulation or precipitation of the grafted polyvinyl alcohol polymer for a period of at least 6 months.

34. A formulation of any preceding or subsequent embodiment/feature/aspect, wherein the formulation has a pH of about 2 to about 3, and

wherein the grafted polyvinyl alcohol polymer is in a coagulated form.

35. A formulation of any preceding or subsequent embodiment/feature/aspect, wherein the formulation has a pH of about 4 to about 5.5, and

wherein the grafted polyvinyl alcohol polymer is in a semi-coagulated form.

36. A formulation of any preceding or subsequent embodiment/feature/aspect, wherein the formulation has a pH of about 5.5 to about 8, and

wherein the grafted polyvinyl alcohol polymer is in amorphous dissolved form.

37. A formulation of any preceding or subsequent embodiment/feature/aspect, wherein the grafted polyvinyl alcohol polymer is soluble in the aqueous phase in an amount of at least 10g/100g water.

38. A formulation of any preceding or subsequent embodiment/feature/aspect, wherein the formulation contains less than 1 wt% surfactant.

39. A formulation of any preceding or subsequent embodiment/feature/aspect, wherein the formulation is surfactant free.

40. A method of making a grafted polyvinyl alcohol polymer of any preceding or subsequent embodiment/feature/aspect, the method comprising:

at least one of an aliphatic carboxylic acid, an aliphatic amide, an aminoalkyl (meth) acrylate, and a hydroxylated alkyl (meth) acrylate is polymerized via free radical polymerization in the presence of free polyvinyl alcohol.

41. A method of making an aqueous solution of the grafted polyvinyl alcohol polymer of any preceding or subsequent embodiment/feature/aspect, the method comprising:

adding a base to the dispersion to raise the pH of the dispersion to 4 to 8 and form an aqueous solution of the grafted polyvinyl alcohol polymer, wherein

The dispersion comprises:

an aqueous phase; and

a grafted polyvinyl alcohol polymer dispersed in an aqueous phase, wherein, prior to said addition, the dispersion has a pH of 2 to 3 or 2 to 5.

42. Process for creping a fibrous web comprising:

providing a rotating cylindrical dryer comprising a dryer surface,

applying a formulation comprising the grafted polyvinyl alcohol polymer of any preceding or subsequent embodiment/feature/aspect to a dryer surface,

the fiber web is conveyed towards the surface of the dryer,

drying the fibrous web on the dryer surface to form a dried fibrous web, and

the dried fiber web is creped from the dryer surface.

43. The process of any preceding or subsequent embodiment/feature/aspect, wherein the formulation is a dispersion.

44. The process of any preceding or subsequent embodiment/feature/aspect, wherein the formulation has a pH of about 4.5 to about 6.

45. The process of any preceding or subsequent embodiment/feature/aspect, further comprising:

substantially removing formulation from the wrinkled dryer surface.

46. The process of any preceding or subsequent embodiment/feature/aspect, further comprising:

prior to said substantially removing, raising the pH of said formulation on said dryer surface to a pH above 6.

47. Any product or process of a grafted polyvinyl alcohol polymer of any preceding or subsequent embodiment/feature/aspect, wherein the plurality of side chains are free of vinylic monomers.

48. Any product or process of a grafted polyvinyl alcohol polymer of any preceding or subsequent embodiment/feature/aspect, wherein the plurality of side chains are substantially free of vinylic monomers.

49. Any product or process of a grafted polyvinyl alcohol polymer of any preceding or subsequent embodiment/feature/aspect, wherein the plurality of side chains are solely acrylic monomers.

The invention may comprise any combination of these different aspects, features, or embodiments set out above and/or below in sentences and/or paragraphs. Any combination of features disclosed herein is considered part of the invention and there is no limitation as to the features that may be combined.

Applicants specifically incorporate the entire contents of all cited references into this disclosure. Further, when an amount, concentration, or other value or parameter is given as either a range, preferred range, or a list of upper preferable values and lower preferable values, this is to be understood as specifically disclosing all ranges formed from any pair of any upper range limit or preferred value and any lower range limit or preferred value, regardless of whether ranges are separately disclosed. In the recitation of numerical ranges herein, unless otherwise indicated, the range is intended to include the endpoints thereof, and all integers and fractions within the range. It is not intended that the scope of the invention be limited to the specific values recited when defining a range.

It will be apparent to those skilled in the art that various modifications and variations can be made to the embodiments of the present invention without departing from the spirit or scope of the invention. Thus, it is intended that the present invention cover the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.

Claims

wherein one or more of said side chains from the plurality of side chains comprises one or more units selected from: an aliphatic carboxylic acid, an aliphatic amide, an aminoalkyl (meth) acrylate, a hydroxylated alkyl (meth) acrylate, or any combination thereof.

2. The grafted polyvinyl alcohol polymer of claim 1, wherein one or more of the side chains from the plurality of side chains comprises: aliphatic carboxylic acid units, aliphatic amide units, aminoalkyl (meth) acrylate units, and hydroxylated alkyl (meth) acrylate units.

3. The grafted polyvinyl alcohol polymer of claim 1, wherein one or more of the side chains from the plurality of side chains comprises an aliphatic carboxylic acid unit.

4. The grafted polyvinyl alcohol polymer of claim 1, wherein one or more of the side chains from the plurality of side chains comprises aliphatic amide units.

5. The grafted polyvinyl alcohol polymer of claim 1, wherein one or more of the side chains from the plurality of side chains comprises hydroxylated alkyl (meth) acrylate units.

6. The grafted polyvinyl alcohol polymer of claim 1, wherein one or more of the side chains from the plurality of side chains comprises: aliphatic carboxylic acid units and aliphatic amide units.

7. The grafted polyvinyl alcohol polymer of claim 1, wherein one or more of the side chains from the plurality of side chains comprises: aliphatic carboxylic acid units and hydroxylated alkyl (meth) acrylate units.

8. The grafted polyvinyl alcohol polymer of claim 1, wherein one or more of the side chains from the plurality of side chains comprises: aliphatic amide units and hydroxylated alkyl (meth) acrylate units.

9. The grafted polyvinyl alcohol polymer of claim 1, wherein the grafted polyvinyl alcohol polymer has a viscosity of less than 500cP s when present in an aqueous dispersion having a pH of 3 at a concentration of 22.5 to 25 wt% at 25 ℃ and 1 atmosphere.

10. The grafted polyvinyl alcohol polymer of claim 1, wherein the grafted polyvinyl alcohol polymer has a viscosity of less than 100cP s when present at a concentration of 2.5 to 10 wt.% in an aqueous solution having a pH of 3 at 25 ℃ and 1 atmosphere.

11. The grafted polyvinyl alcohol polymer of claim 1, wherein the grafted polyvinyl alcohol polymer is dispersible in aqueous solution at a concentration of 10% to 40% by weight.

12. The grafted polyvinyl alcohol polymer of claim 1, wherein the grafted polyvinyl alcohol polymer is capable of being dispersed in an aqueous solution and forming a stable aqueous dispersion that does not exhibit coagulation or precipitation of the grafted polyvinyl alcohol polymer over a period of at least 6 months at 25 ℃ and 1 atmosphere.

13. The grafted polyvinyl alcohol polymer of claim 1, wherein the grafted polyvinyl alcohol polymer is capable of being in a coagulated form when present in an aqueous solution having a pH of about 2 to about 5, is capable of being in a semi-coagulated form when present in an aqueous solution having a pH of about 4 to about 5.5, and is capable of being in an amorphous form when present in an aqueous solution having a pH of about 5.5 to about 8.

14. The grafted polyvinyl alcohol polymer of claim 1, wherein the grafted polyvinyl alcohol polymer has one or more of the following properties:

a) the grafted polyvinyl alcohol polymer is a latex;

b) the grafted polyvinyl alcohol polymer is capable of being completely dispersed in water in an amount of 1 to 25 wt% at a pH of 2-5;

d) the grafted polyvinyl alcohol polymer is gel-free at a pH of 8.

15. The grafted polyvinyl alcohol polymer of claim 1, wherein the grafted polyvinyl alcohol polymer has a first glass transition temperature of-40 ℃ to 60 ℃, and a second glass transition temperature of 70 ℃ to 90 ℃.

16. The grafted polyvinyl alcohol polymer of claim 1, wherein the grafted polyvinyl alcohol polymer has a weight average molecular weight of from 5,000 daltons to about 1,500,000 daltons.

17. The grafted polyvinyl alcohol polymer of claim 1, wherein the grafted polyvinyl alcohol polymer has a number average molecular weight of from 1,000 daltons to about 50,000 daltons.

18. The grafted polyvinyl alcohol polymer of claim 1, wherein the grafted polyvinyl alcohol polymer has a polydispersity Mw/Mn of at least 1.5.

19. The grafted polyvinyl alcohol polymer of claim 1, wherein the polyvinyl alcohol backbone in unreacted form has a weight average molecular weight of from about 5,000 daltons to about 1,500,000 daltons.

20. The grafted polyvinyl alcohol polymer of claim 19, wherein the molecular weight distribution is a unimodal, bimodal, or multimodal molecular weight distribution.

21. The grafted polyvinyl alcohol polymer of claim 1, wherein the polyvinyl alcohol backbone in unreacted form has a number average molecular weight of from about 1,000 daltons to about 50,000 daltons.

22. The grafted polyvinyl alcohol polymer of claim 1, wherein the polyvinyl alcohol backbone in unreacted form has a polydispersity Mw/Mn of 2 to 7.

23. The grafted polyvinyl alcohol polymer of claim 1, wherein the polyvinyl alcohol backbone has a degree of hydrolysis of from about 74 mole% to about 95 mole%.

24. The grafted polyvinyl alcohol polymer of claim 1,

25. The grafted polyvinyl alcohol polymer of claim 1,

wherein the aliphatic carboxylic acid is present and is methacrylic acid,

wherein an aliphatic amide is present and is acrylamide, and

26. The grafted polyvinyl alcohol polymer of claim 1, comprising the structure (I):

-[CH₂-CH(OH)]_a-[CH₂-CH(R])]_b-(I)

wherein each R is an acetate or a side chain from the plurality of side chains.

27. The grafted polyvinyl alcohol polymer of claim 1, comprising the structure (II):

28. A formulation comprising:

an aqueous phase; and

the grafted polyvinyl alcohol polymer of claim 1.

29. The formulation of claim 28, wherein the formulation comprises:

100 parts by weight of an aqueous phase; and

10 to 40 parts by weight of a grafted polyvinyl alcohol polymer, wherein

The grafted polyvinyl alcohol polymer is dispersed in the aqueous phase.

30. The formulation of claim 28, wherein the formulation is a stable aqueous dispersion that does not exhibit coagulation or precipitation of the grafted polyvinyl alcohol polymer for a period of at least 6 months.

31. The formulation of claim 28, wherein the formulation has a pH of about 2 to about 5, and

wherein the grafted polyvinyl alcohol polymer is in a coagulated form.

32. The formulation of claim 28, wherein the formulation has a pH of about 4 to about 5.5, and

wherein the grafted polyvinyl alcohol polymer is in a semi-coagulated form.

33. The formulation of claim 28, wherein the formulation has a pH of about 5.5 to about 8, and

wherein the grafted polyvinyl alcohol polymer is in amorphous dissolved form.

34. The formulation of claim 28, wherein the grafted polyvinyl alcohol polymer is soluble in the aqueous phase in an amount of at least 10g/100g water.

35. The formulation of claim 28, wherein the formulation contains less than 1% by weight of surfactant.

36. The formulation of claim 28, wherein the formulation is surfactant free.

37. A method of making the grafted polyvinyl alcohol polymer of claim 1, the method comprising:

38. A method of making an aqueous solution of the grafted polyvinyl alcohol polymer of claim 1, the method comprising:

The dispersion comprises:

an aqueous phase; and

a grafted polyvinyl alcohol polymer dispersed in an aqueous phase, wherein, prior to said addition, the dispersion has a pH of 2 to 5.

39. Process for creping a fibrous web comprising:

providing a rotating cylindrical dryer comprising a dryer surface,

applying to a dryer surface a formulation comprising the grafted polyvinyl alcohol polymer of claim 1,

the fiber web is conveyed towards the surface of the dryer,

drying the fibrous web on the dryer surface to form a dried fibrous web, and

the dried fiber web is creped from the dryer surface.

40. The process of claim 39, wherein the formulation is a dispersion.

41. The process of claim 40, wherein the formulation has a pH of about 4.5 to about 6.

42. The process of claim 40, further comprising:

substantially removing formulation from the wrinkled dryer surface.

43. The process of claim 42, further comprising:

44. The grafted polyvinyl alcohol polymer of claim 1, wherein the plurality of side chains are free of vinyl monomers.

45. The grafted polyvinyl alcohol polymer of claim 1, wherein the plurality of side chains are substantially free of vinylic monomers.

46. The grafted polyvinyl alcohol polymer of claim 1, wherein the plurality of side chains are solely acrylic monomers.